Last week we moved our cifs share from a Netapp filer to a Ceph disk mounted on a virtual windows server handling the share. After that, we configured the share and changed the DNS Alias to the new IP on the Windows server. Now every Windows and Mac client is able to mount the new share with the new dns alias – except the Linux clients, which got some errors like:

mount error(5): Input/output error
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)

On Windows machines file sharing can work via the computer name, with or without full qualification, or by the IP Address. By default however, file sharing will not work with DNS aliases (in our case just the Linux clients). To enable filesharing to work with DNS aliases, you must make registry changes and reboot the machine.

The solution for this is setting “DisableStrictNameChecking” to allow other machines to use filesharing via the DNS Alias. This change will allow other machines on the network to connect to the machine using any arbitrary hostname:

Add the value “DisableStrictNameChecking” of type DWORD and set it to 1:


On Windows Server 2008 R2:
Add the value “DnsOnWire” of type DWORD and set it to 1


This change will not allow a machine to connect to itself via a hostname. For that you need “BackConnectionHostNames” to allow a server machine to use filesharing with itself via the DNS Alias.

Add a new Multi-String Value “BackConnectionHostNames”


In the Value data box, type the CNAME or the DNS alias, that is used for the local shares on the computer, and then click OK.

Note: Type each host name on a separate line.

Martin Schuster

Autor: Martin Schuster

Martin gehört zu den Urgesteinen bei NETWAYS und leitet zusammen mit Sebastian das Managed Services Team. Vorher war er bei 100world als Systems Engineer angestellt. Während er früher Nürnbergs Partykönig war, ist er nun stolzer Papa und verbringt seine Freizeit damit das Haus zu renovieren.